List of longest tunnels in the world

This list of longest tunnels in the world ranks tunnels that are at least 13 km (43,000 ft) long. Only continuous tunnels are included, pipelines (also buried) are excluded. The longest have been constructed for water distribution, followed by tunnels for railways. Both uses are highly sensitive to gradients.

The total system will have a length of 47.8 km, of which 43.71km is underground and 4.09km is on viaducts. North section of the line is in operation. In 2016 south section: airport El Prat / Collblanc will be in operation.